* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: 'Helvetica Neue', Helvetica, 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', '微软雅黑', Arial, sans-serif;
  background-color: #f0f2f5;
}

.page-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 20px;
}

.course-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 20px;
  margin-top: 20px;
}

.category-section {
  margin-bottom: 40px;
}

.category-title {
  font-size: 24px;
  font-weight: bold;
  margin-bottom: 20px;
  color: #303133;
}

.task-item {
  padding: 15px;
  border: 1px solid #dcdfe6;
  border-radius: 4px;
  margin-bottom: 10px;
  background: white;
}

.comment-item {
  padding: 15px;
  border-bottom: 1px solid #ebeef5;
}

.comment-item:last-child {
  border-bottom: none;
}

.auth-container {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
}

.auth-card {
  width: 400px;
  padding: 40px;
  background: white;
  border-radius: 8px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}